Base unit and disk drive apparatus

ABSTRACT

A base member includes a recessed portion arranged to extend in radial directions and recessed upward from a lower surface of the base member, the radial directions being directions perpendicular to a vertical direction or directions parallel to these directions; and a hole portion arranged to pass through the recessed portion in the vertical direction. The recessed portion includes a recessed portion loop-shaped surface being a loop-shaped surface perpendicular to the vertical direction. A connector is arranged on a lower side of the recessed portion to cover the hole portion. An adhesive is arranged between the connector and the recessed portion. A minimum value of a gap distance between an outer end of the connector and an inner end of the recessed portion in a radial direction in which the outer end of the connector and the inner end of the recessed portion are opposed to each other with the adhesive therebetween is greater than a minimum value of a gap distance between an upper surface of the connector and the recessed portion loop-shaped surface in the vertical direction, in which the upper surface of the connector and the recessed portion loop-shaped surface are opposed to each other with the adhesive therebetween.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2015-257080 filed on Dec. 28, 2015. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a base unit for use in a disk driveapparatus.

Description of the Related Art

Disk drive apparatuses, such as, for example, hard disk drive (HDD)apparatuses, are often arranged to rotate disks at high speeds. In suchan apparatus, each disk receives resistance caused by a gas enclosed inthe apparatus, and this may cause a vibration of the disk and an errorin reading or writing, an increase in a power consumption of a motor, orother problems. In particular, in recent years, the storage capacity ofHDD apparatuses or the like has been increasing, and the number of diskshas been increasing, and it has become important to take measuresagainst the above problems.

Accordingly, instead of air, a gas (which may be hereinafter referred toas a low-density gas) having a density lower than that of air is sealedin a known disk drive apparatus to reduce the aforementioned resistanceduring rotation of the disk. As this low-density gas, helium or the likeis used, for example.

In such a disk drive apparatus, it is important to improve the sealingin of the low-density gas. JP-A 2008-171482, for example, discloses adisk drive apparatus including a base and a cover, and having alow-density gas sealed in a housing space defined by the base and thecover fixed to each other. In this disk drive apparatus, a feedthrough,which is a connector of one type, is joined to the base through a solderso as to close an opening defined in the base to prevent the low-densitygas from leaking out of the base through the opening.

However, as noted in JP-A 2008-171482, a flange of the feedthrough andthe base have different coefficients of thermal expansion, andtherefore, an application of a stress to a solder joint with low stressresistance might cause a crack in the solder joint, resulting in afailure to sufficiently seal in the low-density gas.

It is thus conceivable to use an adhesive which is more resistant toheat shock than the solder and is also inexpensive as a material forjoining the base and the connector to each other.

SUMMARY OF THE INVENTION

A base unit according to a preferred embodiment of the present inventionis a base unit for use in a disk drive apparatus in which a gas having adensity lower than that of air is sealed in a housing space defined by abase member and a cover fixed to each other. The base unit includes thebase member, the base member being arranged to support a motor rotatableabout a central axis extending in a vertical direction; and a connectorelectrically connected to a wire arranged in the housing space. The basemember includes a recessed portion arranged to extend in radialdirections and recessed upward from a lower surface of the base member,the radial directions being directions perpendicular to the verticaldirection or directions parallel to these directions; and a hole portionarranged to pass through the recessed portion in the vertical direction.The recessed portion includes a recessed portion loop-shaped surfacebeing a loop-shaped surface perpendicular to the vertical direction. Theconnector is arranged on a lower side of the recessed portion to coverthe hole portion. An adhesive is arranged between the connector and therecessed portion. A minimum value of a gap distance between an outer endof the connector and an inner end of the recessed portion in a radialdirection in which the outer end of the connector and the inner end ofthe recessed portion are opposed to each other with the adhesivetherebetween is greater than a minimum value of a gap distance betweenan upper surface of the connector and the recessed portion loop-shapedsurface in the vertical direction, in which the upper surface of theconnector and the recessed portion loop-shaped surface are opposed toeach other with the adhesive therebetween.

The base unit according to a preferred embodiment of the presentinvention is able to improve the sealing in of the low-density gas in astructure in which the connector is fixed to the base member through theadhesive.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of a disk drive apparatus accordingto a preferred embodiment of the present invention.

FIG. 2 is a top plan view of a base unit according to a preferredembodiment of the present invention.

FIG. 3 is a bottom plan view of the base unit.

FIG. 4 is an exploded perspective view of an airtight structure realizedby a connector, illustrating a base member as viewed from below,according to a preferred embodiment of the present invention.

FIG. 5 is a side sectional view of the connector and a bottom portionfixed to each other taken along a line that does not pass through anycollar portion according to a preferred embodiment of the presentinvention.

FIG. 6 is a side sectional view of the connector and the bottom portionfixed to each other taken along a line that passes through any collarportion according to a preferred embodiment of the present invention.

FIG. 7 is a graph illustrating example relationships between a gapdistance between the connector and the base member and the amount of aleakage of sealed-in helium.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, exemplary preferred embodiments of the present inventionwill be described with reference to the accompanying drawings. It isassumed herein that a direction in which a central axis about which aspindle motor is rotatable extends is referred to by the term “verticaldirection”, “vertical”, or “vertically”, and that directionsperpendicular to the vertical direction and directions parallel to thesedirections are each referred to by the term “radial direction”,“radial”, or “radially”. It is also assumed herein that a directionalong a circular arc centered on the central axis is referred to by theterm “circumferential direction”, “circumferential”, or“circumferentially”. It is also assumed herein that the side on which acover is arranged with respect to a base member is an upper side in thevertical direction. The shape of each member or portion and relativepositions of different members or portions will be described based onthe above assumptions. Note, however, that the above definitions of thevertical direction and the upper and lower sides are simply made for thesake of convenience in description, and should not be construed torestrict the orientation of a base unit or a disk drive apparatusaccording to any preferred embodiment of the present invention when inuse.

FIG. 1 is a vertical sectional view of a disk drive apparatus 1according to a preferred embodiment of the present invention. The upperside in FIG. 1 corresponds to the upper side in the vertical direction.The disk drive apparatus 1 is an apparatus arranged to perform readingand writing of information from or to magnetic disks 4 while rotatingthe magnetic disks 4. The disk drive apparatus 1 includes a base unit 2,a spindle motor 3, the magnetic disks 4, a cover 5, and an accessportion 6.

The base unit 2 includes a base member 21 arranged to support thespindle motor 3, and a connector 22. The spindle motor 3 is capable ofrotating about a central axis J1. The spindle motor 3 is arranged torotate the magnetic disks 4, which are three in number, about thecentral axis J1 while supporting the magnetic disks 4. The spindle motor3 and the access portion 6 are accommodated in a housing space of a casedefined by the base member 21 and the cover 5. The access portion 6 isarranged to move heads 61 along recording surfaces of the magnetic disks4 to perform the reading and the writing of information from or to themagnetic disks 4.

The cover 5 is joined and fixed to the base member 21 on the upper sideof the base member 21. A junction of the base member 21 and the cover 5is sealed by a sealant, such as an elastomer, or an adhesive, or throughwelding, for example. In addition, a gas having a density lower thanthat of air is sealed in the housing space of the case defined by thebase member 21 and the cover 5. As the low-density gas, a helium gas, anitrogen gas, a mixture of helium and nitrogen gases, or the like ispreferably used. This contributes to reducing resistance applied to eachmagnetic disk 4, and thus to reducing vibrations of the magnetic disks 4which occur during rotation, and minimizing an increase in a powerconsumption of the motor 3.

Note that the disk drive apparatus 1 may alternatively be arranged toinclude one, two, or more than three magnetic disks. Also note that theaccess portion 6 may alternatively be arranged to perform only one ofthe reading and the writing of information from or to the magnetic disks4.

The spindle motor 3 includes a stator 31, a rotating portion 32, and astationary portion 33. The stator 31 includes coils 311. The stator 31is fixed to an outer circumference of a bearing fixing portion 213 ofthe base member 21. The bearing fixing portion 213 is arranged toproject upward from a bottom portion 211 of the base member 21 to assumea substantially cylindrical shape.

The rotating portion 32 includes a rotor hub 321 and a rotor magnet 322.A shaft hole portion 321A extending in the vertical direction is definedin a center of the rotor hub 321. The rotor hub 321 is arranged tosupport the magnetic disks 4. The stationary portion 33 includes a shaft331, a first cone portion 332, and a second cone portion 333. The shaft331 is inserted through the shaft hole portion 321A of the rotor hub321. The shaft 331 is inserted and fixed in an opening portion 213Adefined inside of the bearing fixing portion 213, and is thus held whilebeing oriented in the vertical direction along the central axis J1. Eachof the first and second cone portions 332 and 333 is fixed to the shaft331. While the spindle motor 3 is running, a fluid dynamic pressure isgenerated in a lubricating oil in a gap between the rotor hub 321 andeach of the first and second cone portions 332 and 333. The rotor hub321 is thus supported to be rotatable with respect to the shaft 331.

The access portion 6 includes the heads 61, arms 62, and a head actuatormechanism 63. Two of the heads 61 and two of the arms 62 are providedfor each one of the magnetic disks 4. Each of the two arms 62 supportsone of the heads 61. Each head is arranged to perform the reading andthe writing of information while being arranged in close proximity tothe corresponding magnetic disk 4. The head actuator mechanism 63 isarranged to actuate each of the arms 62 to move an associated one of theheads 61 relative to a corresponding one of the magnetic disks 4. Thehead 61 is thus arranged to make access to a desired location on therotating magnetic disk 4 while being arranged in close proximity to themagnetic disk 4, to carry out the reading and the writing ofinformation. Note that the head 61 may be arranged to perform at leastone of the reading and the writing of information from or to themagnetic disk 4.

FIG. 2 is a top plan view of the base unit 2. The base member 21 of thebase unit 2 is a metal member made of, for example, aluminum. The bottomportion 211 and a side wall portion 212 of the base member 21 are moldedby a die casting process as a single continuous monolithic member.

The side wall portion 212 includes a partially cylindrical side surface212A. The partially cylindrical side surface 212A is a portion of aninside surface of the side wall portion 212. The partially cylindricalside surface 212A is a portion of a cylindrical surface centered on thecentral axis J1. The partially cylindrical side surface 212A is arrangedopposite to an outer circumference of each magnetic disk 4, which isarranged inside of the partially cylindrical side surface 212A. Thepartially cylindrical side surface 212A is defined inside of the sidewall portion 212 by a cutting process, and is coated with a coatingagent through electrodeposition coating. Note that the above coatingusing the coating agent is not limited to the electrodeposition coating,but may alternatively be accomplished through spray coating or the like,for example. This is also true of coating of another portion which willbe described below as being accomplished through electrodepositioncoating.

The base member 21 includes the bottom portion 211. The bottom portion211 includes a disk opposing bottom surface 211A. The disk opposingbottom surface 211A is a portion of an upper surface of the bottomportion 211. The disk opposing bottom surface 211A is a portion of asubstantially annular surface centered on the central axis J1. The diskopposing bottom surface 211A is arranged opposite to a lower surface ofthe magnetic disk 4 arranged above. The disk opposing bottom surface211A is defined by a cutting process after the die casting process, andis coated with a coating agent through electrodeposition coating.

The shaft 331 of the spindle motor 3 is fixed to the bearing fixingportion 213 as suggested above. The bearing fixing portion 213 isdefined inside of the disk opposing bottom surface 211A by a cuttingprocess.

After the die casting process, a head actuator mechanism fixing portion214 is defined by a cutting process at a position away from thepartially cylindrical side surface 212A and the disk opposing bottomsurface 211A. The head actuator mechanism fixing portion 214 is arrangedto project upward from the bottom portion 211. The head actuatormechanism fixing portion 214 is arranged to rotatably fix a portion ofthe head actuator mechanism 63.

FIG. 3 is a bottom plan view of the base unit 2. An FPC mounting portion211B is defined in a lower surface of the bottom portion 211. The FPCmounting portion 211B is a portion slightly recessed upward and on whicha first FPC (a flexible printed circuit board), which is not shown, ismounted. The FPC mounting portion 211B is defined in the vicinity of theshaft 331 when viewed from below.

Here, a control circuit board (not shown) is fixed to the lower surfaceof the bottom portion 211 on the lower side in FIG. 3. Various circuitsare formed on the control circuit board. The control circuit board iselectrically connected to one end portion of the first FPC mounted onthe FPC mounting portion 211B. Lead wires extending from the coils 311(see FIG. 1) included in the stator 31 are electrically connected toanother end portion of the first FPC. This allows electric currents tobe supplied from a drive circuit formed on the control circuit board tothe coils 311 through the first FPC to drive the spindle motor 3 torotate.

In addition, a hole portion 215 (see FIG. 2) passing through the bottomportion 211 in the vertical direction is defined in the bottom portion211 at a position away from the head actuator mechanism fixing portion214. The connector 22, which is defined by a feedthrough, is fixed tothe lower surface of the bottom portion 211 through an adhesive. In thesituation in which the connector 22 is thus fixed, terminals T1 arrangedin an upper surface of the connector 22 are exposed upwardly through thehole portion 215. Terminals T2 (see FIG. 3) each of which corresponds toa separate one of the terminals T1 are arranged in a lower surface ofthe connector 22. The control circuit board is arranged to cover thelower surface of the connector 22, and is electrically connected to eachterminal T2.

Here, as illustrated in FIG. 1, the disk drive apparatus 1 includes anFPC connector 7 and a second FPC 8. The FPC connector 7 is arranged onthe upper side of the bottom portion 21. A portion of the FPC connector7 is passed through the hole portion 215 to be electrically connected toeach terminal T1. The FPC connector 7 is electrically connected to oneend portion of the second FPC 8. Another end portion of the second FPC 8is electrically connected to the head actuator mechanism 63.

This enables a signal read by any of the heads 61 to be transmitted fromthe head actuator mechanism 63 to the control circuit board through thesecond FPC 8, the FPC connector 7, and the connector 22, and alsoenables a signal to be written by any of the heads 61 to be transmittedfrom the control circuit board to the head actuator mechanism 63 throughthe connector 22, the FPC connector 7, and the second FPC 8. It is alsomade possible to transmit a drive signal from the drive circuit formedon the control circuit board to a voice coil motor (not shown) includedin the head actuator mechanism 63 through the connector 22, the FPCconnector 7, and the second FPC 8.

Next, an airtight structure realized by the connector 22, which isdefined by the feedthrough, to seal in the low-density gas will now bedescribed in detail below. FIG. 4 is an exploded perspective view of theairtight structure realized by the connector 22, illustrating the basemember 21 as viewed from below. That is, the lower side in FIG. 4corresponds to the upper side.

The bottom portion 211 of the base member 21 includes a recessed portion216 which extends in radial directions and is recessed upward from thelower surface of the bottom portion 211. The recessed portion 216includes a recessed portion loop-shaped surface S, which is aloop-shaped surface perpendicular to the vertical direction. Therecessed portion 216 is recessed in two steps from the lower surface ofthe bottom portion 211. Accordingly, the recessed portion loop-shapedsurface S includes a first recessed portion loop-shaped surface S1,which is defined by a first-step recess, and a second recessed portionloop-shaped surface S2, which is defined by a second-step recess.

The hole portion 215, which passes through an area enclosed by thesecond recessed portion loop-shaped surface S2 in the verticaldirection, is defined in the bottom portion 211. In other words, thebase member 21 includes the hole portion 215 passing through therecessed portion 216 in the vertical direction. The second recessedportion loop-shaped surface S2 is arranged on the side of the firstrecessed portion loop-shaped surface S1 closer to the hole portion 215.

The bottom portion 211 includes collar portions 217A, 217B, and 217Ceach of which is recessed upward and projects in a radial direction froman outer circumference of the recessed portion 216. The collar portions217A and 217B are arranged to project from opposed sides of an outerperipheral edge of the recessed portion 216. The collar portion 217C isarranged to project from a side that joins the above opposed sides. Theextent to which each of the collar portions 217A to 217C is recessed issmaller than the extent to which the first recessed portion loop-shapedsurface S1 is recessed in the recessed portion 216.

The connector 22 includes a plate-shaped base portion 221 and a bodyportion 222 arranged to project downward from the base portion 221. Theterminals T2 are arranged in a lower surface of the body portion 222.The terminals T1 (see FIG. 2), which are not shown in FIG. 4, arearranged in an upper surface of the base portion 221. The base portion221 includes projecting portions 221A, 221B, and 221C each of which isarranged to project in a radial direction from an outer circumferencethereof. The projecting portions 221A, 221B, and 221C correspond to thecollar portions 217A, 217B, and 217C, respectively. Although, in thepresent preferred embodiment, the collar portions 217A to 217C arearranged at three positions, and the projecting portions 221A to 221Care arranged at three corresponding positions, this is not essential tothe present invention. For example, only two collar portions parallel toeach other and only two projecting portions parallel to each other maybe arranged, and also, collar portions and projecting portions may bothbe arranged at more than three positions.

A method by which the connector 22 is fixed to the base member 21 willnow be described below. Note that, when the connector 22 is fixedthereto, a lower surface of the base member 21 is arranged to face in adirection opposite to the direction of gravity (that is, the directionof gravity points downward in FIG. 4). An adhesive is applied onto thefirst recessed portion loop-shaped surface S1 such that the adhesivewill extend all the way around the hole portion 215. As this adhesive,an anaerobic adhesive, for example, is used. With the adhesive appliedon the first recessed portion loop-shaped surface S1, the projectingportions 221A to 221C of the connector 22 are pressed against uppersurfaces of the collar portions 217A to 217C, respectively. Theconnector 22 is thus arranged on the lower side of the recessed portion216 to cover the hole portion 215. The adhesive intervenes between theconnector 22 and the recessed portion 216. The projecting portions 221Ato 221C are arranged in the collar portions 217A to 217C, respectively.As a result of the adhesive being cured, the connector 22 is fixed tothe base member 21. The adhesive preferably includes at least one of aglass bead and a metal filler to achieve an improvement in the sealingin of the low-density gas.

FIG. 5 is a side sectional view of the connector 22 and the bottomportion 211 fixed to each other taken along a line that does not passthrough any of the collar portions 217A to 217C. As illustrated in FIG.5, an adhesive 9 is arranged between the base portion 221 of theconnector 22 and the recessed portion 216. The adhesive 9 intervenesbetween an outer end of the base portion 221 and an inner end of therecessed portion 216 and between the upper surface of the base portion221 and the first recessed portion loop-shaped surface S1.

A minimum value of a gap distance X between the outer end of the baseportion 221 and the inner end of the recessed portion 216 in a radialdirection in which the outer end of the base portion 221 and the innerend of the recessed portion 216 are opposed to each other with theadhesive 9 therebetween is greater than a minimum value of a gapdistance Y between the upper surface of the base portion 221 and thefirst recessed portion loop-shaped surface S1 in the vertical direction,in which the upper surface of the base portion 221 and the firstrecessed portion loop-shaped surface S1 are opposed to each other withthe adhesive 9 therebetween.

Here, FIG. 7 is a graph illustrating example relationships between thegap distance between the connector and the base member and the amount ofa leakage of sealed-in helium (which is an example of the low-densitygas). The horizontal axis in FIG. 7 represents minimum values (which are0.1 mm, 0.2 mm, and 0.3 mm) of the gap distance between the connectorand the base member. The vertical axis in FIG. 7 represents the amountof the leakage of helium sealed in the housing space defined by the basemember and the cover.

Hatched areas in FIG. 7 represent the amount of a leakage due to a causeother than the gap (for example, a leakage through the connector itself,a leakage due to a hole through which a coil wire of the motor is drawnout, or the like). In the case where the connector is fixed to the basemember through a solder, the solder is arranged in the gap. Asillustrated in FIG. 7, the amount SL of a leakage of helium in this casedoes not depend on the gap distance, but corresponds to an amountrepresented by each hatched area. That is, in the case where theconnector is fixed to the base member through the solder, the amount ofthe leakage of helium through the gap is substantially zero regardlessof the size of the gap.

In contrast, in the case where the connector is fixed through anadhesive, the adhesive is arranged in the gap. The amount of a leakageof helium through the gap in this case is represented by a black area inFIG. 7. That is, the sum total of the amount of the leakage representedby the hatched area and the amount of the leakage represented by theblack area corresponds to the total amount of the leakage of helium. Asillustrated in FIG. 7, the amount of the leakage through the gap asrepresented by the black area decreases as the gap distance decreases.Thus, when the gap distance has a large value, 0.3 mm, the total amountof the leakage of helium exceeds a tolerance threshold value Th. Then,when the gap distance is reduced to 0.2 mm and 0.1 mm, the total amountof the leakage is below the tolerance threshold value Th. Therefore,when the minimum value of the gap distance between the connector and thebase member is arranged to be 0.2 mm or less, the total amount of theleakage of helium does not exceed the tolerance threshold value Th.Adjustment of the gap distance is important when not a solder but anadhesive is used to fix the connector.

As described above, in the present preferred embodiment, the minimumvalue of the gap distance X as illustrated in FIG. 5 is arranged to begreater than the minimum value of the gap distance Y, and therefore, anarrow gap having the gap distance Y can be defined, and the adhesive 9can be forced into this gap by capillary action. The minimum value ofthe gap distance X is arranged to be, for example, 0.5 mm, and theminimum value of the gap distance Y is arranged to be, for example, 0.2mm or less. This contributes to effectively preventing the low-densitygas sealed in the housing space defined by the base member 21 and thecover 5 from leaking out through the hole portion 215 and the gap havingthe gap distance Y.

Further, because the adhesive 9 is actively forced toward the upper sideof the base member 21 by capillary action, the likelihood that theadhesive 9 will leak out to the lower side of the base member 21 isreduced. This in turn reduces the likelihood that a portion of theadhesive 9 will leak out to be attached to the control circuit board,causing a failure of the spindle motor 3 to rotate or anothermalfunction.

Furthermore, the adhesive 9, which is pressed by the connector 22 at thetime of the adhesion of the connector 22, travels longer distances innarrower gaps. Therefore, the adhesive 9 can be actively forced into thenarrow gap having the gap distance Y, which is defined in the presentpreferred embodiment.

Although, in FIG. 5, a surface R1 of the adhesive 9 on the side closerto the hole portion 215 is defined between the upper surface of the baseportion 221 and the first recessed portion loop-shaped surface S1, thesurface R1 may alternatively be defined between the upper surface of thebase portion 221 and the second recessed portion loop-shaped surface S2.This allows the adhesive 9 to be more actively forced toward the upperside of the base member 21.

A portion of a surface R2 of the adhesive 9 on the side opposite to theside closer to the hole portion 215 is defined between the upper surfaceof the base portion 221 and the first recessed portion loop-shapedsurface S1. At the time of the adhesion of the connector 22, theadhesive 9 does not easily travel in the wider gap having the gapdistance X, and the adhesive 9 can be actively forced into the narrowergap having the gap distance Y.

The recessed portion loop-shaped surface S is arranged to have a degreeof surface roughness greater than the degree of surface roughness of theupper surface of the base portion 221. This contributes to preventingthe adhesive 9 from leaking out to the upper side of the base member 21through the hole portion 215 after traveling along the recessed portionloop-shaped surface S.

Each of the outer end of the base portion 221 and the inner end of therecessed portion 216 is arranged to have a degree of surface roughnessgreater than the degree of surface roughness of the upper surface of thebase portion 221. This contributes to preventing the adhesive 9 fromleaking out to the lower side of the base member 21 to be attached tothe control circuit board or the like.

FIG. 6 is a side sectional view of the connector 22 and the bottomportion 211 fixed to each other taken along a line that passes throughany of the collar portions 217A to 217C. In the following description,the collar portion 217A is chosen as a representative for the sake ofconvenience. As illustrated in FIG. 6, at the time of the adhesion ofthe connector 22, the adhesive 9 is pressed by the base portion 221, andan upper surface of the projecting portion 221A is pressed against anupper surface of the collar portion 217A. This easily achieves thepositioning of the connector 22 in the vertical direction.

As a result, the adhesive 9 intervenes between the upper surface of thebase portion 221 and the first recessed portion loop-shaped surface S1,and between an outer end of the projecting portion 221A and an inner endof the collar portion 217A. In addition, the adhesive 9 also intervenesin a very narrow gap between the upper surface of the projecting portion221A and the upper surface of the collar portion 217A.

While preferred embodiments of the present invention have been describedabove, the preferred embodiments may be modified in various mannerswithout departing from the scope and spirit of the present invention.

For example, the connector used to seal in the low-density gas is notlimited to the feedthrough as described above, but may alternatively bea connector defined by a low temperature co-fired ceramic (LTCC).

Also note that an additional first-step recess having a loop-shapedsurface arranged at a level lower than that of the first recessedportion loop-shaped surface S1 according to the above-describedpreferred embodiment may be defined all the way around the hole portion215. In this case, the recessed portion includes three recessed portionloop-shaped surfaces. In this case, the base portion of the connector isnot provided with the projecting portions, and an outer edge portion ofthe base portion is pressed against the loop-shaped surface of the aboverecess all the way around the hole portion 215 to accomplish theadhesion of the connector.

Preferred embodiments of the present invention are applicable to diskdrive apparatuses, such as, for example, HDDs.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A base unit for use in a disk drive apparatus inwhich a gas having a density lower than that of air is sealed in ahousing space defined by a base member and a cover fixed to each other,the base unit comprising: the base member, the base member beingarranged to support a motor rotatable about a central axis extending ina vertical direction; and a connector electrically connected to a wirearranged in the housing space; wherein the base member includes: arecessed portion arranged to extend in radial directions and recessedupward from a lower surface of the base member, the radial directionsbeing directions perpendicular to the vertical direction or directionsparallel to these directions; and a hole portion arranged to passthrough the recessed portion in the vertical direction; the recessedportion includes a recessed portion loop-shaped surface being aloop-shaped surface perpendicular to the vertical direction; theconnector is arranged on a lower side of the recessed portion to coverthe hole portion; an adhesive is arranged between the connector and therecessed portion; and a minimum value of a gap distance between an outerend of the connector and an inner end of the recessed portion in aradial direction in which the outer end of the connector and the innerend of the recessed portion are opposed to each other with the adhesivetherebetween is greater than a minimum value of a gap distance betweenan upper surface of the connector and the recessed portion loop-shapedsurface in the vertical direction, in which the upper surface of theconnector and the recessed portion loop-shaped surface are opposed toeach other with the adhesive therebetween.
 2. The base unit according toclaim 1, wherein the recessed portion loop-shaped surface is arranged tohave a degree of surface roughness greater than a degree of surfaceroughness of the upper surface of the connector.
 3. The base unitaccording to claim 1, wherein each of the outer end of the connector andthe inner end of the recessed portion is arranged to have a degree ofsurface roughness greater than a degree of surface roughness of theupper surface of the connector.
 4. The base unit according to claim 1,wherein the adhesive includes at least one of a glass bead and a metalfiller, and wherein the recessed portion loop-shaped surface is arrangedto have a degree of surface roughness greater than a degree of surfaceroughness of the upper surface of the connector.
 5. The base unitaccording to claim 1, wherein the adhesive includes at least one of aglass bead and a metal filler, and wherein each of the outer end of theconnector and the inner end of the recessed portion is arranged to havea degree of surface roughness greater than a degree of surface roughnessof the upper surface of the connector.
 6. A base unit for use in a diskdrive apparatus in which a gas with a density lower than that of air issealed in a housing space defined by a base member and a cover fixed toeach other, the base unit comprising: the base member that supports amotor rotatable about a central axis extending in a vertical direction;and a connector electrically connected to a wire in the housing space;wherein the base member includes: a recessed portion that extends inradial directions and is recessed upward from a lower surface of thebase member, the radial directions being perpendicular or substantiallyperpendicular to the vertical direction; and a hole portion that passesthrough the recessed portion in the vertical direction; the recessedportion includes a recessed portion loop-shaped surface defining aloop-shaped surface perpendicular or substantially perpendicular to thevertical direction; the connector is on a lower side of the recessedportion to cover the hole portion; an adhesive is between the connectorand the recessed portion; and a minimum value of a gap distance betweenan outer end of the connector and an inner end of the recessed portionin a radial direction in which the outer end of the connector and theinner end of the recessed portion are opposed to each other with theadhesive therebetween is greater than a minimum value of a gap distancebetween an upper surface of the connector and the recessed portionloop-shaped surface in the vertical direction, in which the uppersurface of the connector and the recessed portion loop-shaped surfaceare opposed to each other with the adhesive therebetween; wherein therecessed portion loop-shaped surface or each of the outer end of theconnector and the inner end of the recessed portion have a degree ofsurface roughness greater than a degree of surface roughness of theupper surface of the connector.
 7. The base unit according to claim 6,wherein a surface of the adhesive on a side closer to the hole portionis defined between the upper surface of the connector and the recessedportion loop-shaped surface.
 8. The base unit according to claim 7,wherein the recessed portion loop-shaped surface includes a firstrecessed portion loop-shaped surface, and a second recessed portionloop-shaped surface located on a side of the first recessed portionloop-shaped surface closer to the hole portion; and the surface of theadhesive is located at the second recessed portion loop-shaped surface.9. The base unit according to claim 6, wherein at least a portion of asurface of the adhesive on a side opposite to a side closer to the holeportion is located between the upper surface of the connector and therecessed portion loop-shaped surface.
 10. A disk drive apparatuscomprising: the base unit of claim 6; the cover; the motor; and anaccess portion that performs at least one of reading and writing ofinformation from or to a disk supported by the motor; wherein the motorand the access portion are accommodated in the housing space.